this might be a stupid question (to some) but...if i disconnect the negative battary terminal when i hook up the battery charger, this will prevent me killing my eletrics?i know you can fry your electrics by hooking up battery chargers and jump leads to your battery so i wanna make sure this is a safe why of doing it ::Risk::
Yes, though if your going to.. ..charge up your battery, you really should remove it from the car. At the very worst, the battery could catch fire, and take the car with it,and while charging, the battery will be venting fumes that will corrode everything around it.
Connecting the charger to a battery Here're few points: 1. Before connecting or disconnecting charger to the battery ensure that your power point is switched OFF.2. Remove the battery from the vehicle or if it's not possible, you must disconnect the battery leads.3. When charging battery other than the sealed type remove the battery filler caps and check the level of liquid (electrolyte) in the cells. If necessary top up with distillated water and ensure that the liquid is 6mm (1/4")above the top of the plates. Do not replace the filler caps until the charging program has been completed.4. Connect clips to battery terminals ensuring they bite firmly and polarity is correct.5. Plug the charger into the mains, switch on power, and note the reading on the charger's ammeter. Note: During the charging process the battery will be gassing and emitting hydrogen gas. Don't use a naked flame near the battery.6. When the battery is being disconnected switch the power OFF before removing the clips from the battery. If you want to start the car from the charger you need the one with the capability of doing so
Lots of info posted already, but a few more things.Charging a battery in an engine bay without disconnecting it can be done safely, if the following is observed.Use a charger with a relatively low max capacity, eg a 4 amp charger. Connect the leads to the battery before turning on the power to the charger. Leave the bonnet open, so that air is free to circulate around the engine bay and battery. Don't leave the charger connected for too long - overnight's OK, but if you've got the opportunity, then only charge for a few hours, then go for a drive, and let the car alternator do the rest of the job. Turn the power of to the charger before disconnecting the leads. Don't forget that the car alternator is capable of supplying MUCH more charging current to the battery than most battery chargers, so the problem of batteries venting fumes is going to be greater while driving than while sitting still and charging. Damaging car electrics by using chargers or jumper leads, although it's possible, is pretty rare. It's not the charging process that is capable of doing any damage, it's the risk of sparks between the battery and the leads causing voltage spikes in the car's electrical system while connecting/disconnecting them. When using jumper leads (some will go into huge detail about exactly which side of which lead needs to be conected to where) the most important thing to remember is to connect the leads firmly to the battery +ve and chassis, without scraping them or allowing them to move, which will cause sparks.If you are concerned about damage from spikes, I've seen 'anti zap' devices at car parts stores for as little as $25 that permanently connect to the battery terminals, and absorb potentially harmful spikes. They are the same thing that can be found on 'anti zap' jumper leads.Lucky last, in my opinion, save the pennies and buy a depleted electrolyte type battery such as an Odyssey or an Optima. Search will reveal quite a few discussions, with pro's and con's, but the best in my book is the extremely low level of venting of acidic gases when compared to normal wet acid batteries, and the high starting current capabilities.
